Piston rod

[qca2003]

We have a problem, one of our compressor the piston rod was crack, it is suspected caused by condenseble material (ie. moisture / water content ). Can someone explain us What is the mechanism of piston rod cracking that caused by condenseble material ?, if true the cracking is caused by condenseble material, what is the condition or parameter that is able to this problem occur ?

 

[unclesyd]

There are a lot of things that could cause your problem, but a little more information is needed. The failure could be from mechanical or corrosion, or other.

What are you compressing?
The rod material of construction?
Where on the rod did it crack/break?
How long was the service life of the rod?
Is the rod plated?

 

[qca2003]

Hi Uncleasyd,

Thank for you comment, following are the answer for your questions :
1. The gas that compressed is mix H2 70 % and CO 30 %.
2. The rod material construction is stainles steel 13 chrom.
3. The rod crack position on the top near piston.
4. The service life still one year.
5. The rod no plated.

 

[unclesyd]

Did the rod crack completely or only partially through?
If the rod is only partially crack see if you can break it open and examine the fracture surface.
You may have to cut into the bad side. Do not disturb the fracture surface, keep fingers and tools off of it.
Can you take a hardness reading on the piston rod and compare with your specifications?
If there was condensate or liquid present you probably have torn up a lot more
Have you checked the threads on the crosshead end?
Where did the crack originate?
What are the operating conditions, temp, pressure?
Was this an OEM piston rod or a replace part from a different source?

 

[Compositepro]

The connection between a piston rod cracking and compressing condensible material is that you will get liquid condensing in the cylinder during the compression stroke. When the piston gets to the top of its stroke it will be pushing liquid out instead of gas. This can cause the piston to deadhead with damage to the piston or shaft. Gas compessors are not designed to pump liquids. Although the designs are similar they operate at different speeds.